1. Field of the Invention
The present invention relates to a composite engine mount suitable for use in a vehicle body for supporting a transversely mounted engine, that is, an engine which is mounted to a vehicle with its axis directed perpendicular to the longitudinal axis of the vehicle.
2. Description of the Related Art
When an engine mount is used as a left-hand or right-hand mount for supporting a transversely mounted engine, the engine mount must bear the loads from the engine in every direction, that is, in the front and rear, left and right, and vertical directions. In particular, the vehicle body defines three orthogonal directions: a longitudinal direction, a transverse direction perpendicular to the longitudinal direction, and a vertical direction perpendicular to the plane defined by the longitudinal and transverse directions. Therefore, the engine mount must include at least one stopper which can act or bear loads in every direction.
Japanese Utility Model Publication SHO No. 58-175230 discloses an engine mount including a stopper which can act in only one horizontal direction of either front and rear or left and right direction. Japanese Utility Model Publication SHO No. 59-131636 discloses an engine mount including only a vertical stopper. Because the stoppers are provided in the liquid chambers within the metal members of the engine mounts, an excessive orifice effect would happen. In this meaning, a stopper is preferable to be provided outside a metal member.
FIGS. 13 and 14 illustrate a hypothetical composite engine mount 100 which has been developed from the disclosed in Japanese Utility Model Publication SHO No. 58-175230. FIG. 15 illustrates relationships in arrangement among composite engine mount 100, a space 140 to be provided for composite engine mount 100 and a fixed member 120 of a vehicle located adjacent to composite engine mount 100. The hypothetical mount is not a known mount but helps to understand the drawbacks included in engine mounts. In the composite engine mount 100 including a metal member 101 and a rubber member 102 fixed to metal member 101, an engine-side bracket 103 is coupled to rubber member 102 while a body-side bracket 104 is coupled to metal member 101. A gas chamber 105, an orifice 106, a diaphragm 107, a separator 108 and a liquid chamber 109 are provided within a space defined by metal member 101 and rubber member 102. A front and rear, left and right and vertical bounce or bound stopper 112 which should not be provided in liquid chamber 109 is provided outside metal member 101 and is fixed to an upper end portion of metal member 101. There is no rebound stopper. Because stopper 112 is located outside metal member 101, a bound stopper clearance a, a front stopper clearance d and a rear stopper clearance e are considerably large, and space 140 is larger than a space 130 which is to be provided for a composite engine mount 10 of the present invention illustrated hereinafter.
There are the following drawbacks in such mounts which will be easily understood referring to the hypothetical mount of FIGS. 13, 14 and 15:
(i) Since stopper 112 is located outside metal member 101, sufficient clearances a, d and e must be provided between composite engine mount 100 and the adjacent member 120 and space 140 to be provided for mount 100 is large. As a result, an overhang amount H of mount 100, that is, a distance between a center of mount 100 and a coupling portion 150 between bracket 103 and an engine-side member is larger than an overhang L of a mount 10 in accordance with the present invention. Also, an offset amount I of mount 100, that is, a distance in the direction perpendicular to an overhang direction between the center of mount 100 and coupling portion 150 is large. A large amount of overhang and offset increases the size and weight of the assembly of mount 100 and brackets 103 and 104, decreases the resonance frequency of the assembly and makes it difficult to extract an expected potential from the mount.
(ii) Since the mounts usually do not include a stopper which can act in every direction, the mounts are not suitable for use as a left-hand or right-hand mount for supporting a transversely mounted engine.